Conventionally, a flow control valve for controlling to cut off or allow a flow of a fluid, such as cold water or hot water, is well-known and so constructed that, for example, as shown in FIG. 10, a valve box 103 is provided with an inlet 100 and an outlet 101 for the fluid and houses in a valve chamber 104 a valve body 105 mounted on a driving shaft of a motor 106 and driven thereby to open or close the valve chamber 104 with respect to the inlet 100.
The flow control valve constructed as abovementioned actuates the valve body 105 by an open-close signal given to the motor 106 so as to open or close a passage for the fluid, in which the passage is abruptly open or closed on the basis of the open-close signal so that a flow of the fluid abruptly stops or starts to cause water hammering. As a result, the problem is created in that sounds or vibrations are generated.